.mce-toolbar .mce-i-smiley {
    background: url(../../../wp-includes/images/smilies/simple-smile.png) no-repeat 50% 50%;
    background-size: contain;
}

.mce-smily .mce-grid div {
    font-size: 24px;
    line-height: 1;
    text-align: center;
    width: 1em;
    height: 1em;
    padding: 3px;
    border: 0;
    border-radius: 1px;
    cursor: pointer;
}

.mce-smily .mce-grid div:hover {
    background: #b4b9be;
}

.mce-smily .mce-grid img {
    font-size: inherit;
    width: 1em;
    height: 1em;
    vertical-align: top;
}